Self-contained breathing apparatus are used in many fields, for example, as fully portable compressed air breathing apparatus having a compressed air cylinder. In such cases, breathing gas (e.g., air) flows out of a pressure cylinder as the breathing gas source through a system of lubes or hoses, which are equipped with shut-off and control devices, to a regulator.
A typical use for such fully portable breathing apparatus is as compressed air breathing apparatus for use by firefighters or for industrial applications. Industrial applications, for example, in a petrochemical plant, involve providing protection against toxic gases, particularly hydrogen sulfide. In such cases it can particularly be necessary for the breathing apparatus to be small and lightweight in design so that they will not hinder an escape. However, because chemical plants are becoming increasingly larger, a wearer of an apparatus may need to switch out his breathing gas source and attach a new compressed gas cylinder, for example.